This invention relates to craft guidance systems and is concerned with craft guidance systems using transmitting stations transmitting signals which are received by mobile objects (herein conveniently called "craft") to aid the navigation of those craft.
Many such systems are known (e.g. GEE: DECCA NAVIGATOR: LORAN: OMEGA: CONSOL) in which craft guidance is derived from intersecting hyperbolic lattices. These have become known as hyperbolic systems. The hyperbolae of the lattices are loci of constant phase difference.
The present invention is also a hyperbolic system. It greatly extends the aid which can be derived from known hyperbolic systems in that it may provide continuously, in real time, intended moving positions for craft to follow and control signals to assist them to do so. The movement of such positions may be coordinated and maintained at specific intervals while the speed of movement may be fixed or variable in more than one direction. Communications are provided to pass system information and inform a control centre of the navigational state of craft.